Control method and system in a refrigeration system and compressor of a refrigeration system
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Solution Overview
Problem
Existing refrigeration systems with variable speed compressors in commercial settings face inefficiencies due to the need for electronic thermostats, which increase costs and fail to optimize performance by not accounting for installed capacity or responding to system disturbances, making obsolete the solutions designed for residential use.
Innovation Solution
A control method and system that uses a combination of general and specific logic to measure torques and cycle times, allowing for ON/OFF thermostat control, load stabilization, and disturbance monitoring, enabling the compressor to adjust speed based on user-defined targets and system conditions without additional hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable speed compressors are used in commercial refrigeration systems, then refrigeration capacity can be adjusted to instantaneous demand, but electronic thermostats are required which increase system cost
Solution Approach 1:
The inverter controller is designed to perform multiple functions: it not only controls the compressor speed but also monitors system parameters (current, voltage, frequency, temperature) and implements control logic for load stabilization and disturbance correction. This multi-functionality eliminates the need for separate electronic thermostats while maintaining the ability to adjust refrigeration capacity to instantaneous demand.
Solution Approach 2:
The patent combines the thermostat function with the inverter controller. The inverter controller integrates both the speed control functionality and the temperature monitoring/control functionality that would traditionally require separate electronic thermostat devices. This merging reduces component count and system cost while preserving variable speed capability.
2Productivity
If variable speed compressors with inverter control are implemented, then compressor capacity can be adjusted, but efficiency is not optimized because the system does not account for installed capacity or respond to disturbances
Solution Approach 1:
The system implements feedback control by continuously monitoring system parameters including current, voltage, frequency, and temperature. The inverter controller uses this feedback information to adjust compressor speed dynamically, optimizing efficiency based on actual system conditions rather than operating at fixed speeds. The feedback mechanism enables the system to respond to disturbances and maintain optimal performance.
Solution Approach 2:
The patent implements dynamic speed control where the compressor operates at variable speeds determined by real-time system conditions. The inverter controller continuously adjusts the compressor speed based on instantaneous demand and system state, allowing the system to adapt dynamically rather than operating at fixed speeds. This dynamic operation optimizes efficiency across different operating conditions.
3Device complexity
If ON/OFF compressor control is used, then system cost is reduced, but temperature homogenization time increases and system performance is reduced
Solution Approach 1:
The patent applies partial action by using a simplified control logic that operates effectively without full electronic thermostat functionality. The inverter controller implements sufficient speed adjustment capability to achieve temperature homogenization without requiring complex additional control systems. This partial implementation of control functionality reduces cost while maintaining acceptable performance.
Data Source
AI summary
A control method and a control system for a compressor in a refrigeration system, implements control logic based on the monitoring of parameters of the refrigeration system, where these parameters may include, for example, a previous load (Cant), a current load (Catu), a reference load (Cref), a measured cycle time (tcycle) and a target time (ttarget).